During optical and ophthalmological examinations, in order to explore specific functions of the visual apparatus, including stereoscopic vision, the patient needs to be shown different stimuli for each eye in binocular vision. The present systems use polarized or coloured filters. These are physically made up of two sheets. Two differently polarized filters (vertical and horizontal polarization) are placed side by side on the display surface, so that each filter covers half of it. The patient wears goggles, whose right lens has the same polarization as the filter covering the right portion of the screen, and the same goes for the left lens, so that each eye can only see the corresponding portion of the screen. This solution, in tests which dissociate between right and left eye, halves the portion of the screen seen by each eye and makes overlapping of stimuli impossible. Moreover, this methodology does not enable to take into account the correct convergence between the eyes, invalidating the quality and correctness of the examination, especially in tests with three-dimensional images, in which the slight deviation of the two eyes allows fusion of images into one vision, providing the perception of depth and of stereoscopic sight. According to a further methodology of the known art, differently coloured filters are used for each eye. In healthy subjects, a high degree of dissociation between the two eyes can be achieved, and stimuli can overlap, but these stimuli are chromatically altered, and in case of chromatic imbalance (for example colour blindness) this cannot lead to reliable results. Moreover, this methodology proves completely useless in three-dimensional tests because, as previously stated, these tests aim at showing each eye the same image, perceived from two different points of view without inducing any chromatic alteration between the two visions. In another technical field, and precisely in the field of cinematic vision, a very complex and expensive system was developed (commonly called by the name of the commercial product I-MAX), which entails the alternate projection of two image flows. The viewer wears special goggles, which are synchronized with the two projectors and alternately dim the two lenses so that the viewer's right eye always perceives the images projected by projector number one, and similarly, the left eye always perceives the images projected by projector number two. These images represent the same object, yet seen from two conveniently different points; moreover, the frequency of commutation of the lenses, and hence of the projectors, is high enough to prevent the eye from detecting the same commutation.